Giant high temperature superelasticity in Ni53Mn24Ga21Co1Cu1 microwires

Abstract Ni-Mn-Ga is commonly used as a room temperature shape memory alloy. With the doping of Co and Cu, its phase transformation temperature increased to around 500 K, which can be used as high temperature shape memory alloys, and the superelasticity and shape memory strains are improved as well. Here, giant recoverable strain 16.3% is reported in a Heusler type Ni53Mn24Ga21Co1Cu1 microwire, prepared by rapid solidification via the Taylor-Ulitovsky method, with a diameter of 140 μm. Within a 150 K temperature range, the microwire maintains superelastic property of more than 10%. It has high cycle stability and the superelasticity remains almost unchanged after 100 cycles test at 523.15 K. It was also found that the energy loss density of the heat treated microwire is about twice than that of as-prepared microwire.